TBitmap.Dormant Method

Creates a memory bitmap image in order to release the bitmap handle, forcing the image into DIB format to save resources.

Pascal

procedure Dormant;

C++

__fastcall Dormant();

Description

Use Dormant to change the format of the bitmap in memory thereby reducing the amount of GDI resources used by the application.

Dormant creates a bitmap image in memory using a memory stream object. This preserves the image so that the bitmap can then free the HBITMAP (accessed through the Handle property) that was assigned to it.

DIB handles may use fewer Win95 GDI resources than DDB, but DIBs may also use more memory than DDBs, depending on the current video driver and mode.

C++ Examples:

Copy Code

/*
This example uses a button on a form and creates two bitmaps
dynamically.  One bitmap is monchrome, which means all
non-white colors become black.  The bitmap file path is
relative to the Debug directory.
Note: For the C++ Builder, capitalization matters for the file
name and path.
*/
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Graphics::TBitmap *Bitmap1 = new Graphics::TBitmap();
  Graphics::TBitmap *Bitmap2 = new Graphics::TBitmap();
  try
  {
    Bitmap1->LoadFromFile("..\\FACTORY.BMP");
    Bitmap2->Assign(Bitmap1);     // Copy Bitmap1 into Bitmap2
    Bitmap2->Dormant();           // Free up GDI resources
    Bitmap2->FreeImage();         // Free up Memory.
    Canvas->Draw(20,20,Bitmap2);  // Note that previous calls don't lose the image
    Bitmap2->Monochrome = true;
    Canvas->Draw(80,80,Bitmap2);
    Bitmap2->ReleaseHandle();       // This will actually lose the bitmap;
  }
  catch (...)
  {
    MessageBeep(0);
  }
  delete Bitmap1;
  delete Bitmap2;
}

Delphi Examples:

Copy Code

{
This example uses a button on a form and creates two bitmaps
dynamically.  One bitmap is monchrome, which means all
non-white colors become black.  The bitmap file path is
relative to the Debug directory.
}
procedure TForm1.Button1Click(Sender: TObject);
var
 BitMap1,BitMap2 : TBitMap;
 MyFormat : Word;
begin
   BitMap2 := TBitMap.Create;
   BitMap1 := TBitMap.Create;
try
   BitMap1.LoadFromFile('factory.bmp');
   BitMap2.Assign(BitMap1);     // Copy BitMap1 into BitMap2
   BitMap2.Dormant;             // Free up GDI resources
   BitMap2.FreeImage;           // Free up Memory.
   Canvas.Draw(20,20,BitMap2);  // Note that previous calls don't lose the image
   BitMap2.Monochrome := true;
   Canvas.Draw(80,80,BitMap2);
   BitMap2.ReleaseHandle;       // This will actually lose the bitmap;
 finally
   BitMap1.Free;
   BitMap2.Free;
 end;
end;